Archives par mot-clé : Antarctic

The West Antarctic Ice Sheet, a landbound mass of ice larger than Mexico, experienced substantial surface melt through the austral summer of 2015-2016 during one of the largest El Niño events of the past 50 years, according to scientists who had been conducting the first comprehensive atmospheric measurements in the region since the 1960s.

A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.

The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change’s (IPCC) 2013 report, which says that Antarctica is overall losing land ice.

According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.

As we did in the previous two posts, we will examine each proxy and reject any that have an average time step greater than 130 years or if it does not cover at least part of the Little Ice Age (LIA) and the Holocene Climatic Optimum (HCO). We are looking for coverage from 9000 BP to 500 BP or very close to these values. Only simple statistical techniques that are easy to explain will be used.

The Marcott, et al. 2013 worldwide reconstruction has its problems, but many of the proxies used in the reconstruction are quite good and very usable.

The Antarctic reconstruction created here is comparable to previous temperature reconstructions, especially those focusing on eastern Antarctica. It shows two climatic optima, one from 11500 BP to 9000 BP and another from 6000 BP to 3000 BP. In eastern Antarctica, using our proxies, the later optimum is warmer. But, in other areas the earlier optimum is warmer, however, the difference is small

Ms Korpanty said global climate underwent significant change about 14 million years ago when the Antarctic ice sheet expanded.

“The new study presents shallow-marine sediment records from the Australian continental shelf, providing the first empirical evidence linking high-altitude cooling around Antarctica to climate change in the subtropics during the Miocene era,” she said.

An international team of researchers, led by the UK Centre for Polar Observation and Modelling at the University of Leeds, are the first to map the change in ice speed. The team collated measurements recorded by five different satellites to track changes in the speed of more than 30 glaciers since 1992.

Glacier flow at the southern Antarctic Peninsula has increased since the 1990s, but a new study has found the change to be only a third of what was recently reported.

In light of all the above, the evidence is clearly mounting against those who point to warming on the Antarctic Peninsula as proof of CO2-induced global warming. For in the most incredible manner, warming trends that were once among the highest recorded on earth have slowed and even reversed to show cooling.

in Science of the Total Environment 580: 210-223, 2017 , Recent regional climate cooling on the Antarctic Peninsula and associated impacts on the cryosphere.

The unusually high Esperanza temperature is likely the result of a strong jet stream that brought a strong ridge of high pressure over the Antarctic Peninsula, allowing warm air from South America to push southwards over Antarctica. Antarctic sea ice was at record-highs in 2014 and again in 2015 when modern records were shattered.

Here we use a stacked temperature record to show an absence of regional warming since the late 1990s. The annual mean temperature has decreased at a statistically significant rate, with the most rapid cooling during the Austral summer. Temperatures have decreased as a consequence of a greater frequency of cold, east-to-southeasterly winds, resulting from more cyclonic conditions in the northern Weddell Sea associated with a strengthening mid-latitude jet.

Here we use a stacked temperature record to show an absence of regional warming since the late 1990s. The annual mean temperature has decreased at a statistically significant rate, with the most rapid cooling during the Austral summer. Temperatures have decreased as a consequence of a greater frequency of cold, east-to-southeasterly winds, resulting from more cyclonic conditions in the northern Weddell Sea associated with a strengthening mid-latitude jet.

Scambos, who is about to travel to Antarctica for research, and other scientists said they don’t see other key signs that this growing crack would result in a catastrophic collapse of the entire shelf. A chunk of ice will break off, “But it’s not going to lead to a runaway disintegration,” he said Friday.